This invention relates to the chemical control of tobacco suckers (i.e., axillary buds) via the application of certain trans-2-[1-(3-chloroallyloxy-amino)ethylidene]-5-(substituted thioalkylidene)-cyclohexane-1,3-dione derivatives.
Tobacco crop management requires that the terminal growing meristem be removed so that the number of usable leaves and their quality can be optimized. The removal of the terminal meristem, a process called topping, leads to the rapid development of lateral buds. These lateral buds are known as suckers. For maximum yield, the suckers have to be removed either manually or inhibited by chemical means. A further discussion on the growth and control of tobacco suckers can be found on pages 71-81 of Plant Growth Regulating Chemicals Vol. II, Ed. L. G. Nickell, CRC PRESS (1983).
In the chemical control of tobacco suckers, it is important that the chemical operates systemically; i..e, it should inhibit sucker development even when applied to other parts of the tobacco plant. This is important because in field-grown tobacco, the axillary buds, or suckers, are hidden in large leaf whorls. Thus, it is very difficult to apply the chemical spray such that it will directly contact the axillary buds. However, if the chemical operates systemically, it can be effectively applied to the leaves of the tobacco plant or even as a soil drench.
The most commonly used chemical for tobacco sucker control is maleic hydrazide. This systemic inhibitor, though effective, is not without its problems. Treatment with maleic hydrazide tends to leave undesirably high levels of residues in the leaves.
U.S. Pat. No. 4,440,566, issued Apr. 3, 1984, disclosed compounds having the formula: ##STR1##
wherein R is most preferably alkyl of 3 to 3 carbon atoms, most preferably ethyl or propyl;
R.sup.1 is most preferably 3-trans-chloroallyl or 4-chlorobenzyl;
R.sup.2 and R.sup.3 are preferably each alkyl of 1 to 3 carbon atoms or one of R.sup.2 or R.sup.3 is hydrogen and the other is alkylthioalkyl having 2 through 8 carbon atoms, most preferably R.sup.2 and R.sup.3 are each methyl or one of R.sup.2 or R.sup.3 is hydrogen and the other is 2-ethylthiopropyl.
This patent teaches that these compounds exhibit herbicidal activity against grasses and are safe with respect to broadleaf crops and also may be employed to prevent or retard the growth of lateral buds in plants and to promote the thinning out of fruit in various fruit trees.